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The Science Behind the Tests

What are PCR, LAMP, Antigen Lateral Flow and Test to Release tests?

PCR Test
PCR (Polymerase Chain Reaction) is considered to be the gold standard for Covid-19 testing. PCR offers the most reliable results as it can detect small quantities of Covid-19 genetic material (RNA) in a sample. The test requires a sample that is normally collected from the nose and/or throat. Once the sample reaches the lab, a series of chemicals are added to it. If the virus is present a reaction occurs whereby many copies of the genetic material are created, allowing for detection and analysis by scientists. This allows for the confirmation of whether or not the virus is present, and if someone is currently infected.

A LAMP (Loop-mediated Isothermal Amplification) test is analysed in a laboratory like the RT-PCR test is, but the test is less accurate and sensitive. Therefore, it may give a negative result to people who have a small amount of virus present. A negative LAMP test provides you with some confidence, but not as much as a PCR test.

The RT-LAMP SARS-CoV-2 (COVID-19) RNA detection is by oropharyngeal and nasopharyngeal swab, which means it involves samples from the throat and nose. Processing the sample occurs at a laboratory managed by Prenetics using the Oxsed RAViD Direct SARS-CoV-2 assay.

LAMP is a different type of COVID-19 test from PCR and Lateral Flow. It is less sensitive and accurate than PCR but more sensitive and accurate than a Lateral flow test.
Only a handful of countries accept this as a test to enter their country so it’s important that you check the suitability of this test before booking.
Results should be ready 2hrs (120mins) after your test, however we advise you to leave 4hrs between testing and your flight in case you allow for any re-testing.

(Antigen) Lateral Flow Test
An antigen lateral flow test is a quick and simple method to test people who do not have symptoms of COVID-19, but may still be spreading the virus. A lateral flow test allows for the detection of “antigens” produced by the Covid-19 virus. With a lateral flow test samples are analyzed on the spot with a small device (like a home pregnancy test kit) that gives a result in 30 minutes. Antigen lateral flow tests can be carried out at home, with no need for further processing by a lab. If the result from the Antigen Lateral flow test is positive then a PCR test must be carried out.

A negative result does not guarantee that you do not have coronavirus (due to the viral load being below the level of detection). Antigen lateral flow tests are not analysed in a laboratory like the PCR and LAMP tests are.

ExpressTest use the Roche Biosensor Nasal COVID-19 Antigen Lateral Flow Rapid Test. The sensitivity and specificity rates for this test are:
Diagnostic Sensitivity: 96.52% (95% CI: 91.33% -99.04%)
Diagnostic Specificity: 99.68% (95% CI: 98.22% -99.99%)
Positive predictive value (PPV): 97.5%
Negative predictive value (NPV): 98.3% (95% CI: 94.0% -99.5%)

Test to Release Test (TTR)

Currently, if you have travelled to a country/territory on the Amber list in the 10 days prior to arriving into England, and do not qualify for the double vaccination exemption, you must quarantine for 10 days on arrival. Note: Requirements may differ in Wales and TTR is not available currently in Scotland.
Test to Release is a voluntary scheme that allows you to pay for a private COVID-19 PCR test on day 5. If the result is negative (and the result of the day 2 test result was negative), then your quarantine can end. The test can’t be taken until 5 days after your arrival into England. It is still compulsory to take a PCR test on or after day 8 unless you qualify for the double vaccination exemption.

You cannot use the Test to Release scheme if you’ve been in or through a country on the red list in the 10 days before your arrival.

Our Test to Release Test is bookable as part of our Amber Arrivals Test Package either as a bundle, or separately if you want to decide later.

For more information, visit the UK Government website.

What's the difference between an RT-PCR test and an Antigen Lateral Flow test?

RT-PCR detects the presence of viral RNA and the Antigen Lateral flow detects the presence of viral proteins or antigens.

NB: Not all RT-PCR tests are equivalent. The DHSC requirements for Day 2 arrival RT-PCR test are different from other RT-PCR tests, such as PCR Fit to Fly. PCR is a methodology that uses assay reagents, which can have very different performance characteristics such as sensitivity, specificity or limit of detection. It could target one or multiple genes, for example. It might also need different buffer (liquid) used for the sample collection (when customers are swabbed) to ensure that all the tests required by DHSC (such as sequencing for the identification of variants of concern for positive Day 2 samples) can be carried out.

What's the difference between an antibody and antigen test?

An antibody test detects if you have already had the virus by checking for the presence of COVID-19 antibodies in your immune system. An antigen test only detects the virus that is currently in your body. As part of our ExpressTest service, we offer Reverse Transcription Polymerase Chain Reaction (RT-PCR) antigen tests and Antigen Lateral Flow tests which detect the presence of the virus.

Are your swabbing practitioners medically qualified?

Our swabbing practitioners have all undergone training in how to administer and process swabbing and are monitored by senior swabbing practitioners.

What about vaccines?

If I have had a COVID-19 vaccine, will I test positive for COVID-19 on a viral test?

No. None of the recently authorised and recommended vaccines in the UK can cause you to test positive on viral tests (like our RT-PCR test), which are used to see if you have a current infection.​

I've been vaccinated now - do I still need a test?

The likelihood is that you may still need to get tested, depending on the country you are travelling to and the airline/transport company's testing requirements. If you are travelling to England, the following travellers will no longer need to self-isolate when they return to England from an Amber-list country (except if returning from France):

- UK residents who are fully vaccinated through the UK vaccine rollout under the UK Governments vaccination programme
- those vaccinated in the USA with a vaccine authorised by the Food and Drug Administration (FDA) for the USA
- those vaccinated in Europe with a vaccine authorised by the European Medecines Agency (EMA) for Europe or SwissMedic for Switzerland.

Fully vaccinated means a full 14 days have passed since the final dose of COVID-19 vaccine was given.

Like all medicines, no vaccine is completely effective, so you should continue to take recommended precautions to avoid infection. Some people may still carry COVID-19 despite having had a vaccination, and potentially pass it to someone who is not yet fully vaccinated. Other countries have different regulations in relation to vaccines and travel, so it is advisable you check with your airline and your destination country's advice.

Will your ExpressTest RT-PCR tests detect the new variants of COVID-19?

Yes, our RT-PCR tests have been specifically designed to focus on highly conserved regions of the viral RNA. The variations or mutations do not impact the sensitivity or specificity of our tests. As always, we will continue to monitor the science to provide a highly effective and accurate test result.

Does it hurt having a swab taken?

It is a quick test and doesn't hurt but can be uncomfortable.

What should I do if I test positive for COVID-19?

Because you have tested positive for COVID-19, this means that you have the virus. You should leave the testing centre straight away and return to the place you are staying, without delay. You need to self-isolate for a period of ten days from the date of your positive test. You may wish to contact the NHS for further guidance on self-isolation or call them on 111.

Notification to UK Public Health Authorities is as follows:

Public Health England (PHE)
In England, we are obliged by law to notify your positive test result and personal details to the relevant health authority. They may contact you via their Track & Trace contact tracing programme.

Public Health Scotland (PHS)
In Scotland, you should take an NHS PCR test to confirm the positive lateral flow result. The NHS PCR result will be reported into PHS and they may contact you via their Test and Protect contact tracing programme.

You will not receive a refund for any cancelled arrivals tests as positive samples require additional processing to check for variants of COVID-19.

Why Choose Us?

Our first concern is for our customer’s safety and welfare. This is why all our tests conform to the highest safety standards and use the latest gold Standard technology to provide you with accurate results and peace of mind.

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